Conventionally, there is known a method for producing a silicon epitaxial wafer by epitaxially growing a silicon epitaxial layer on a front main surface of a silicon single crystal substrate mounted on a spot facing of a susceptor arranged within a reactor.
In a case of producing the silicon epitaxial wafer, a cleaning step of cleaning the silicon single crystal substrate is performed before vapor phase epitaxy of the silicon epitaxial layer. In the cleaning step, generally, an SC1 cleaning step of mainly removing particles is performed using a mixed solution composed of ammonia water and hydrogen peroxide solution and then, an SC2 cleaning step of mainly removing metals is performed using a mixed solution composed of hydrochloric acid and hydrogen peroxide solution. During the SC1 cleaning and the SC2 cleaning, a natural oxide film is formed on a surface of the silicon single crystal substrate.
Thereafter, the cleaned silicon single crystal substrate is carried within the reactor and mounted on the spot facing of the susceptor. Further, heating within the reactor is performed to subject the substrate to hydrogen heat treatment. As a result, the natural oxide film formed on the front main surface of the silicon single crystal substrate is removed by etching using a hydrogen gas. In the hydrogen heat treatment, a hydrochloric gas may be used together with a hydrogen gas.
Next, a temperature within the reactor is set to a growth temperature and a silicon source gas is fed on the front main surface of the silicon single crystal substrate. As a result, the silicon epitaxial layer is epitaxially grown on the front main surface of the silicon single crystal substrate. Thus, the silicon epitaxial wafer is produced.
Further, there is known a wafer supporting apparatus for forming a thin film on a rear surface of a wafer, in which projections for supporting the wafer from its lower surface are provided on tops of lift pins for forming a clearance between the wafer and a susceptor (see, e.g., Patent Document 1).
Patent Document 1: Japanese Patent Application Publication Unexamined Tokukaihei-9-205130